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(No'ModeL) T. A. EDISON. MANUFACTURE OF INGANDESOENT ELECTRIC LAMPS. No.459,835. Patented Sept. 22. 1891.

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UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NENV JERSEY, ASSIGNOR TO THE EDISONELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

MANUFACTURE OF INCANDESCENT ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 459,835, datedSeptember 22, 1891.

Application filed January 22, 1883. Serial No. 82,560. (No model.)

To aZZ whom it may concern.-

Be it known that I, THOMAS A. EDIsoN, of Menlo Park, in the county ofMiddlesex and State of New Jersey, have invented a new and usefulImprovement in the Manufacture of Incandescing Electric Lamps, (Case No.52%,) of which the following is a specification.

In my application No. 525 (Serial No. 78,774) I have set forth a methodby which the inclosing globe of an incandescing electric lamp can becharged With nitrogen at such a pressure as to, prevent electricalcarrying from the carbon filament to the globe. Such method consists inthe removal of the constituents other than nitrogen of the air or othergas contained in the globe by the physical absorption or deposition ofsuch constituents. I have since found that very satisfactory results maybe obtained by the chemical removal of the oxygen from the air containedin the globe by the use of pyrogallate of potassium, cuprous chloride,phosphorus, or equivalent chemical agent, which combines with oxygen,the atmospheric pressure within the globe being first reduced to such apointthat the removal of the oxygen will leave the nitrogen at theproper pressure to prevent the electrical carrying.

The desired degree of pressure is set forth in my application No. 516,Serial No. 77,526. I employ, also, a suitable drying agent-such asphosphoric anl1ydride--to free the nitrogen from moisture. V

In carrying out my invention I may make use of an apparatus such as isillustrated in the accompanying dyawing.

A represents the inclosing globe, and a the flexible carbon filament, ofan incandescing electric lamp. An exhaust-tube b is provided, connectedby an air-tight joint with a tube 15, the lower portion 13 of Whichcontains pyrogallate of potassium, cuprous chloride, phosphorus, orequivalent substance capable of chemically combining with oxygen. Thetube B is provided with a stopcock 0. A tube 0, provided with astop-cock (Z, and a tube D, having a stop-cock 6, extend from the tubeB. The tube O is provided with means for connecting it with an air-pump,and the tube D terminates in a bulb E, containing phosphoric anhydrideor a similar drying agent. The stop-cocks c and a being closed and thecock at open, such a portion of the air is removed from the globe thatthe removal of the oxygen from the remainder will leave the nitrogen ata pressure sufficient to prevent electrical carrying. I then close cland open a, when the oxygen remaining in the globe will combine with thepyrogallate of potassium or other substance used, the Whole of theoxygen being thus gradually removed from the globe. The cock 0 is thenclosed and cock 6 opened, when the moisture of the nitrogen is absorbedby the phosphoric anhydride in the bulb E. The cock 6 must never beopened While cock 0 is also open, for in this case the pyrogallate ofpotassium or other substance would become dry and would then fail tocombine with the oxygen. If phosphorus is used instead of the potassiumcompound, it must be heated. The removal of the oxygen in the globereduces the pressure about one-fifth, leaving the proper pressure in theglobe to prevent electrical carrying. After the nitrogen is reduced tothe proper state the globe is sealed off ath- IVhat I claim is 1. Themethod of obtaining a dry nitrogen atmosphere at a definite pressure inthe inclosing globe of an incandescing electric lamp, consisting inproducing an air-pressure in the globe slightly above the pressure ofnitrogen desired, decomposing the air left in the globe, retaining thenitrogen in the globe, removing the oxygen by putting a receptaclecontaining a substance having affinity for oxygen into communicationwith the globe, and removing the moisture from the nitrogen,substantially as described.

2. The method of ob aining-a dry nitrogen atmosphere at a definitepressure in the inclosing globe of an incandescing electric lamp,consisting in producing an air-pressure in the globe slightly above thepressure of nitrogen desired, decomposing the air left in the globe,retaining the nitrogen in the globe, removing the oxygen, but not thenitrogen, and removing the moisture from the nitrogen, substantially asdescribed.

This specification signed and witnessed this 13th day of January, 1883.

THOS. A. EDISON.

Witnesses:

H. W. SEELY, EDWARD H. PYATT.

